1. Field of the Invention
This invention relates generally to the atomization of fluids and more particularly to the high volume, low pressure atomization and entrainment of liquids, such as paint, for application to a surface.
2. Description of Related Art
Devices which atomize and particulate fluids are widely used in the application of fluids such as paints and other coatings, cleaning solutions, solvents, blasting agents, solvents, sealants, lubricants and pesticides.
Two types of apparatus for the atomization and particulation of fluids are currently in use, namely pneumatic and airless. As they refer to application of paint type coatings, both types normally comprise high pressure apparatus. However, at least one type of low pressure system is also known and comprises the system disclosed in patents granted to the present inventor on Jul. 25, 1989, namely U.S. Pat. No. 4,850,809 entitled, "Air Operated Low Pressure Spraying System." and another patent on a low pressure system granted to the present inventor on Feb. 12, 1991, namely U.S. Pat. No. 4,991,776 entitled, "High Volume, Low Pressure Spraying System." U.S. Pat. Nos. 5,044,557 and 5,058,807 issued to the present inventor on Sep. 3, 1991 and Oct. 22, 1991, respectively, and are entitled "Air Operated Low Pressure Spraying Systems." These patents are specifically incorporated herein by reference.
Conventional high pressure, low volume pneumatic systems have the disadvantage of locally producing a wasteful cloud of fluid and air commonly referred to as "overspray". The solvent vapors become part of the atmosphere and present a hazard not only to the environment and user, but also to the atomizing equipment. The visible components of overspray comprise solids entrapped in the vapor or aerosol which results not only in the degrading of the quality of the work surface, but also in the contamination of the work site. High pressure, airless systems also generate a type of waste referred to as "bounceback". This condition is created by the high velocity by which the fluid is propelled to the surface. The rebounding particles, solids and vapors, form a cloud similar to the overspray generated by pneumatic apparatus. Both types of systems, however, produce the same undesirable and wasteful results.
Overspray and its reduction has become a subject of major concern to industries involved in the atomization of fluids. An amendment to the "Clean Air Act" of February, 1987 as it relates to hydrocarbon emission controls, established limitations and standards of performance for fluid transfer. Those industries affected are manufacturers and end users of commercial and consumer solvents, architectural coatings, pesticides, and all apparatus and methods involved in their application. Particular emphasis is being placed on government and military users. Additionally, individual states are implementing this act with their own pollution control bills. In some states, high pressure paint systems and adaptations that rely on high pressure, low volume application of atomization are being studied for restricted use. This could have a disastrous effect on thousands of small businesses. Manufacturers of fluids, in order to reduce the percentage of carrier solvents, are now required to increase their solids content and change fluid chemistry. This places new burdens on the atomizing system to atomize these high solids and viscosities.
All spraying systems require some type of apparatus to atomize the fluid and deliver it to the work surface. This apparatus is commonly called a spray gun. Guns vary in their configuration, size, weight and internal composition.
Extensions for liquid spraying devices are known. U.S. Pat. No. 1,961,481 disclosed a straight extension conventional paint spraying device with a movable nozzle which delivered a fixed pattern fluid flow of fixed pattern width. U.S. Pat. 3,700,174 disclosed an airless spray gun extension with a curved shank constructed to withstand high pressures of up to 2,500 psi or more.
There is a need for a detachable spraying assembly for a high volume low pressure system which will direct atomized liquid to a targeted position and will apply the liquid in a variety of directions, fluid flows, pattern widths, and fan shapes. Such an assembly should accommodate a diversity of applications, including spraying into areas difficult of access.